Airtac SAILB Rear Lock Cylinder SAILB125X350
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X350 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 350mm stroke and a built-in spring-applied, air-released mechanical lock in the back cover — it holds the load at the retracted (rod-in) stroke end even when air is lost.
- BoreØ125 mm
- Stroke350 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X350
The AirTAC SAILB125X350 is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock housed in the back cover. Because this is a SAILB configuration, the spring-applied, air-released lock engages precisely when the piston reaches the retracted stroke end. Operating at 0.5 MPa, it delivers 6136N of push thrust and 5734N of pull thrust, scaling to 11045N push at 0.9 MPa, making it suited for heavy-duty holding tasks.
This unit operates pneumatically with a 1/2 PT port and a 32mm carbon steel rod threaded M27x2. A critical design detail is that the variable air cushion at the locker end is shorter (24mm) than the free end (40mm). The lock itself provides a static hold without requiring live pressure, and unlocking is achieved automatically via air release or by using the manual release lever.
Airtac SAILB Rear Lock Cylinder SAILB125X350 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X350 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 350 mm |
| Acting type | Double acting, with lock |
| Port size | G1/2 |
| Rod thread | M27×2 |
| Lock type | Spring-applied, air-released (back cover) |
|---|---|
| Unlock | Automatic (air) & manual |
| Operating pressure | 0.15 – 1.0 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 500 mm/s |
| Cushion | Adjustable (40 mm free end / 24 mm lock end) |
| Max stroke | Up to 1500 mm |
Specifications follow the official AirTAC SAIL datasheet (ISO 15552). Confirm against the product label before installation. Port options: PT / G.
How the Lock Holds
The lock is spring-applied and air-released: a spring drives a lock pin into the rod when the release air is removed, so the load is held at the retracted (rod-in) stroke end without live pressure. Supply air to the release port to unlock automatically, or use the manual release lever.
The lock engages only when the piston reaches the stroke terminal on the back-cover side — it is a static end-of-stroke hold, not a mid-stroke clamp and not a moving-rod brake. For locking at any position along the stroke, choose a BSAI clamp-lock instead.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 kgf | |
Cylinder thrust is separate from the lock's holding capability. Actual usable force is lower than theoretical due to friction and back-pressure — size with a margin.
Where the Airtac SAILB Rear Lock Cylinder SAILB125X350 Is Used
Vertical Power-Off Hold
Secures elevated heavy masses in the retracted position instantly when air supply drops, preventing gravity-driven falls on lifting machinery.
Heavy Clamp Retention
Maintains high-force clamping pressure at the rod-in stroke end without consuming continuous compressed air, optimizing energy use.
Safety Gate Locking
Keeps industrial safety barriers and heavy gates locked shut in the retracted terminal position until the release air is actively supplied.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X350 the Right Lock Cylinder?
Choose this 125mm bore model when a heavy load must be physically secured at the retracted rod-in position during power loss; stepping down to an 80mm bore yields 2268N pull at 0.5 MPa, while moving up to a 160mm bore provides 9425N pull. If your application requires clamping at an arbitrary mid-stroke point rather than a stroke-end hold, select the BSAI clamp-lock cylinder instead. The SAIL lock is a static holding device that engages after the cylinder stops, not a dynamic brake for a moving rod.
When integrating this cylinder, avoid using a fast-exhaust valve, as back-pressure on the locker side can unintentionally release the lock; an independent-exhaust solenoid valve is required. For any safety-critical vertical lifting where human safety depends on the load staying up, add an independent safety measure. To replace this unit, match the 125mm bore, 350mm stroke, back locker position, 1/2 PT port, and your desired mounting from the available Basic, FA, FB, CA, CB, CR, LB, TC, FTC, TCM1, or TCM2 options. Given the 350mm stroke, ensure external guides are used to manage side loads and prevent rod binding.
Quick checklist
- ✓ Hold needed at the retracted (rod-in) end?
- ✓ Or lock anywhere → use BSAI
- ✓ Independent-exhaust valve fitted
- ✓ Port/thread type (PT/G)
- ✓ Extra safety measure for people
Airtac SAILB Rear Lock Cylinder SAILB125X350 FAQ
At 0.5 MPa, this 125mm bore cylinder provides 6136N of push force and 5734N of pull force. At 0.9 MPa, the push force increases to 11045N.
The lock is spring-applied and air-released, engaging statically when the piston reaches the retracted stroke end in the back cover. It does not clamp at mid-stroke. Unlocking occurs automatically via air release to the port or manually via the release lever.
Related AirTAC Lock & Standard Cylinders
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